CHAPTER 6 CLOCK GENERATOR
Preliminary User’s Manual U17260EJ3V1UD
135
(3) Internal low-speed oscillation clock (clock for watchdog timer)
•
Internal low-speed oscillator
This circuit oscillates a clock of f
RL
= 240 kHz (TYP.). After a reset release, the internal low-speed oscillation
clock always starts operating.
Oscillation can be stopped by using the internal oscillation mode register (RCM) when “internal low-speed
oscillator can be stopped by software” is set by option byte.
The internal low-speed oscillation clock cannot be used as the CPU clock. The following hardware operates
with the internal low-speed oscillation clock.
•
Watchdog timer
•
TMH1 (when f
RL
, f
RL
/2
7
, or f
RL
/2
9
is selected)
Remark
f
RL
:
Internal low-speed oscillation clock frequency
6.2 Configuration of Clock Generator
The clock generator includes the following hardware.
Table 6-1. Configuration of Clock Generator
Item Configuration
Control registers
Clock operation mode select register (OSCCTL)
Processor clock control register (PCC)
Internal oscillation mode register (RCM)
Main OSC control register (MOC)
Main clock mode register (MCM)
Oscillation stabilization time counter status register (OSTC)
Oscillation stabilization time select register (OSTS)
Oscillators
X1 oscillator
XT1 oscillator
Internal high-speed oscillator
Internal low-speed oscillator